Strain-insulator.



T. VARNEY.

STRAIN INSULATOR.

APPLICATION FILED JAN. 10, 1908.

Patented Oct. 26,1909.

I'NVENTUR y BY [A], 4M

ATTORNEY WITNESSES 1 ("UNITED g li l A T I THEODORE VA'BNEY. orminiseries.-rEN'NsYLVANIAL 'issionon.BY'iunsn-rd essrons, MENTS', 'rowns'rmenonsn ELECTRIC & ivranuriicrumno'.COMPANY: crease- PITTSBURG,PENNSYLVANIA, A CORPORATION or PE NSYLVANIA-1 s'rnn N- nsu'tn'roa. 7

I Specification of. Letters Patent lni (*lilttil (H'i .I. Applicationmediiiuiila 10.1908. Serial No. 410.2291] which may be poured in \tlienLu-it and-"ale,

- and useful Improvement in Strain-lnsula- ;tors, ofwhich the followingis a specifieatifon. I My invention'relates tostrain insulators forelectric lines and it hasfor, its object "to 10 provide a compact anddurableJdevice of j this character that shall bc'capable ofrwitlrstanding str'ains incident to the use of high j voltages and that shallalso embody an 1111- p port. the casing segments and hold them in provedeasing of insulating material.-

tofore constructed, have sometimes comprised metal tubes having taperedends into which insulating tubes and tapered plugs were fitted, themetal-tubes being surrounded by coatingsor'jacketsof molded insulating.material which extended. over the ends of the insulating tubes.

According to my present invention, I provide' an outer casing which isbuiltup of sections and which is so separated from the inner coating orjacket above mentioned that it is entirely freed from the strains towhich the remainder of the insulator is subjected. The outer casing maybe replaced by an other, when desired, and it serves to effec- Y tuallyprotect the insulator proper from the weather.

' Figure 1 of the accompanying drawing is a partially sectionalelevation of a strain insulator constructed in accordance with myinvention and Fig. 2 is an enlarged view of the packed joint between thecasing and the strain parts.

Referring to the drawings, the insulator here illustrated comprises ametal tube 1 having tapered ends, tapered tubes 2 and 3 of insulatingmaterial seated in the ends of the metal tube 1, tapered plugs a and 5seated in the insulating tubes and provided with end projections 6' and7 which extend for a material distance beyond the extremities of theinsulating tubes, and strain loops High volta e strain insulators, ashere- 12 and .13 of porcolaih orother hnird inst preferably formed ofcast. iron \\:hicl.1. arew I 26, isms 1 plugs .4 and 5, maypreferablyJiejlil h-dliw'i'lll:

asphalt gum, or other.insul nting,material.

lowed to sch-by cordingf-tfri o-rdiu'i peratures In order that a 'sti'llhetter,.1 be afforded zt'or the.entirc dea. c131.. a casingll-comprisiug L\\ ';r ,taperedsections:

lating n1atcria],1:and end; caps; I14. and

fitted over-the shanks of the tapered :phi by stuffed oints andwhichserve t'o. sup-a" position. -lhe vadjacent etvtren-iitiesi'of the"segments- 12 and 1 overlap-mud .a1'e am-.1 vided with opposite annularrecesses '16 and 17 which together form an annular groove to be filledwith cement for holding the parts together. The outer extremities of thecasing segments 12 and 13 are provided with annular grooves 18 overwhich the raps 1+ and 15 extend, the caps being secured in place bycement which fills the annular grooves 18 and the spaces between thecaps and the segments.

The central portions of the caps are provided with hollow hubprojections 15,) through which the shanks (land 7 extend and in which asuitable stulling or packing material is located, tight joints beingformed by bushings 20 which are screwed into the hollow hub project-ions19. Although tight joints are formed at the ends of the casing 11, thestrains which are imposed upon the insulator proper are, not imparted tothe casing. Asbestos washers 21 may preferably be 'i11terposed betweenthe casing segments and the caps and also between the two segments.

8 and 9 which are screwed upon the eX- 1 stantlally changing the generalconstruction tance between the plugs and the metal tube.

The iriterior of the insulator, between the The space within the casing1-1 may be-filled with an insulating gum, or similar substance 10, whichis sufiiciently yielding to permit of a slight relative movement betweenthe outer casing and the strain parts.

\Vhile the tapered parts are all provided with conical surfaces, asshown in the drawings, it is conceivable thatmodifications in theircontours may be effected without subor diminishing the usefulness of theinsulator.

Variations in size and arrangement of parts may obviously be effectedwithin the scope of my invention and I desire that only formed ofmetallic and insulating materials on which strains are exerted and asegmental easin therefor having sealed joints and comp etely inclosingsaid parts but relieved from the strains which are exerted upon saidparts.

2. A strain insulator comprising a metal tube having tapered ends,tapered plugs seated in the ends of the tube and insulated therefrom andan inclosin casing therefor of hard insulating materia said casing beinrelieved from the strains to which the ot er parts are subjected.

3. A strain insu ator comprising a metal tube having tapered ends,tapered tubes of insulating material seated in the ends of the metaltube, tapered plugs seated in the insulating tubes and having stems orshanks extending outwardly therefrom and a segmental casing ofinsulating material, the said casin being relieved from the strains towhich t e other arts are subjected.

4. A strain insu ator comprising a metal tubehaving tapered ends,tapered tubes-0f insulating material seated in the ends of the metaltube, tapered plugs seated in the insulating tubes and having stemsextending outwardly therefrom, a molded jacket of insulating materialwhich seals the tube and extends from one stem to the other, and anindependent outer casing which is free from the stirains to which theother parts are subjecte 5. A strain insulator comprising a metal tubehaving tapered ends, tapered tubes of insulating material seated in theends of the metal tube, tapered plugsseated in the tapered tubes andhaving stems extending outwardly therefrom, strain loops attached to thestems, an insulating compound which fills the space in the metal tubebetween the plugs, a molded jacket of insulating material which sealsthe structure and extends from one stem to the other, and an independentinclosing casing therefor comprising a pair of overlapping tubularsegments an end caps that form packed 'oints with the stems.

In testimony w ereof, I have hereunto subscribed my name this 20th dayof Dec.,

THEODORE VARNEY. Vitnesses:

WILLIAM CooPnR, BIRNEY HINES.

